Plasma chambers commonly are used for performing various processes such as chemical vapor deposition, sputter deposition and plasma-enhanced etching processes used in manufacturing an electronic workpiece such as a semiconductor device or flat panel display. Commonly the plasma within a plasma chamber is sustained by coupling RF or DC power from an electrical power source to the plasma. The coupling is accomplished typically by connecting the power source to an electrode within the chamber or to an antenna or magnetic coil within or adjacent to the chamber.
The conditions within a plasma chamber generally change during the progression of the manufacturing process being performed within the chamber, and such changes sometimes cause electrical arcing within the chamber. If any electrical arcing occurs between the plasma and the workpiece being manufactured, or between the plasma any of the chamber components, damage may occur to the workpiece or the chamber components. The risk of damage increases with the duration of the arcing.
To minimize or prevent such damage, there is a need for apparatus that can quickly detect electrical arcing within the plasma chamber or any other abnormality that changes the electrical load impedance that the chamber presents to the power source. In addition, a need exists for apparatus that can suppress (i.e., stop) the arcing while allowing the plasma process to continue with as little interruption as possible.
More generally, there is a need for apparatus that can quickly detect or suppress abnormal changes in an electrical load to which a power source is supplying electrical power.